feat: raw-TCP socket transport (serveTcp / tcpConnect / TransportKind.TCP)

Add a TCP (AF_INET) transport that speaks the raw Arrow-IPC framing
protocol — the network analog of the existing AF_UNIX runner, for
trusted-network co-located workers that want the lean framing without the
HTTP envelope. Mirrors the Python reference (vgi-rpc 8ea49aa).

- src/launcher/serve-tcp.ts: serveTcp(protocol, { host, port, ... }) binds
  (host, port), defaults host to 127.0.0.1 (loopback only), port 0 lets the
  OS auto-select, disables Nagle (setNoDelay) per connection, and emits a
  TCP:<host>:<port> discovery line once bound (after which no more stdout).
  Same per-connection IPC dispatch loop and idle-timeout model as serveUnix.
- src/client/tcp.ts: tcpConnect(host, port) client helper wrapping pipeConnect
  over a connected TCP socket. Node-only (statically imports node:net), so it
  is exported only from the node barrel, never from the runtime-agnostic core
  that browser/workerd bundles re-export.
- TransportKind.TCP; serveTcp reports it via the ServeStartHook / DispatchInfo.
- examples/conformance.ts: --tcp [HOST:]PORT (loopback-default host), prints
  TCP:<host>:<port> — mirrors the --unix / UNIX:<path> launcher contract.
- Focused round-trip tests (test/tcp.test.ts) and rebuilt dist.

Raw TCP carries NO authentication or TLS; it is for trusted networks only and
defaults to loopback (127.0.0.1). Use the HTTP transport for untrusted networks.

Verified cross-language: TS --tcp worker against `vgi-rpc-test --tcp` passes
102 total / 98 passed / 0 failed / 4 skipped — exact parity with the pipe run.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: rustyconover

README.md

@@ -16,7 +16,7 @@ Define RPC methods with Arrow-typed schemas, serve them over stdin/stdout, and i
 - **Runtime introspection** — opt-in `__describe__` method for dynamic service discovery via the CLI
 - **Result validation** — missing required fields in handler results throw descriptive errors at emit time
 - **Authentication** — bearer tokens, JWT, mTLS (PEM-in-header and XFCC), with chainable authenticators
-- **Three client transports** — HTTP, subprocess, and raw pipe, all sharing a unified `RpcClient` interface
+- **Four client transports** — HTTP, subprocess, raw pipe, and raw TCP (`tcpConnect` / `serveTcp`), all sharing a unified `RpcClient` interface. Raw TCP carries no auth/TLS and defaults to loopback (`127.0.0.1`) — trusted networks only; use HTTP otherwise.
 
 ## Installation
 

dist/client/index.d.ts

@@ -4,5 +4,5 @@ export type { OAuthResourceMetadataResponse } from "./oauth.js";
 export { fetchOAuthMetadata, httpOAuthMetadata, parseClientId, parseClientSecret, parseDeviceCodeClientId, parseDeviceCodeClientSecret, parseResourceMetadataUrl, parseUseIdTokenAsBearer, } from "./oauth.js";
 export { PipeStreamSession, pipeConnect, subprocessConnect } from "./pipe.js";
 export { HttpStreamSession } from "./stream.js";
-export type { HttpConnectOptions, LogMessage, PipeConnectOptions, StreamSession, SubprocessConnectOptions, } from "./types.js";
+export type { HttpConnectOptions, LogMessage, PipeConnectOptions, StreamSession, SubprocessConnectOptions, TcpConnectOptions, } from "./types.js";
 //# sourceMappingURL=index.d.ts.map

dist/client/index.d.ts.map

@@ -0,0 +1,19 @@
+import type { RpcClient } from "./connect.js";
+import type { TcpConnectOptions } from "./types.js";
+/**
+ * Connect to a vgi-rpc server over a raw TCP socket and wrap it with
+ * {@link pipeConnect}. The network analog of `subprocessConnect`: identical
+ * lockstep raw Arrow-IPC framing, only the transport differs. Nagle's
+ * algorithm is disabled (`setNoDelay(true)`) so lockstep requests are not
+ * delayed coalescing writes. The returned client's {@link RpcClient.close}
+ * also destroys the socket.
+ *
+ * SECURITY: raw TCP carries **no authentication or TLS** — only connect to
+ * trusted endpoints. Use `httpConnect` for untrusted networks.
+ *
+ * @param host Hostname or IP address of the TCP server.
+ * @param port TCP port of the server.
+ * @param options Optional log/external-location configuration.
+ */
+export declare function tcpConnect(host: string, port: number, options?: TcpConnectOptions): RpcClient;
+//# sourceMappingURL=tcp.d.ts.map

dist/client/tcp.d.ts

@@ -42,6 +42,14 @@ export interface PipeConnectOptions {
     /** External storage config for resolving externalized batches. */
     externalLocation?: import("../external.js").ExternalLocationConfig;
 }
+/**
+ * Options for {@link tcpConnect}, the raw-TCP-socket RPC client.
+ *
+ * SECURITY: raw TCP carries no authentication or TLS — connect only to
+ * trusted endpoints (use {@link httpConnect} for untrusted networks).
+ */
+export interface TcpConnectOptions extends PipeConnectOptions {
+}
 /** Options for {@link subprocessConnect}, which spawns a server process and pipes to it. */
 export interface SubprocessConnectOptions extends PipeConnectOptions {
     /** Working directory for the spawned process. Defaults to the current directory. */

dist/client/tcp.d.ts.map

@@ -1,3 +1,4 @@
+export { tcpConnect } from "./client/tcp.js";
 export * from "./index.core.js";
-export { acquireLock, computeHash as launcherComputeHash, defaultStateDir, type FileLockHandle, type GcResult, gcStateDir, type LaunchConfig, launch, probeSocket, type ServeUnixHandle, type ServeUnixOptions, type SocketPaths, type StatusRow, serveUnix, socketPaths, statusRows, tryAcquireLock, } from "./launcher/index.js";
+export { acquireLock, computeHash as launcherComputeHash, defaultStateDir, type FileLockHandle, type GcResult, gcStateDir, type LaunchConfig, launch, probeSocket, type ServeTcpHandle, type ServeTcpOptions, type ServeUnixHandle, type ServeUnixOptions, type SocketPaths, type StatusRow, serveTcp, serveUnix, socketPaths, statusRows, tryAcquireLock, } from "./launcher/index.js";
 //# sourceMappingURL=index.d.ts.map